nzarano Posted January 12, 2015 Share Posted January 12, 2015 i've had my 240z for about a year now, the engine is original and always gave me trouble, didnt want to start or in general was unreliable, so i thought why not get an l28! a bit more power and hopefully it will be a bit more reliable.... HA! i was wrong... engine blew up within a week of being in the car and i went back to the original l24, which just stopped working recently, so i thought to myself why not take apart the l28 and build something properly. My goal is reliability and fun. I dont want to have to spend a ton of money to get some crazy horsepower or even get to the point where i have to think if the other parts of the car will take the horsepower. In the department of speed i just want to be able to beat my friends bmw 32something wagon in a 0-60 sort of deal, so i think it needs to be sub 6.5 seconds ish? maybe 200hp at the crank? when it comes to funds im more interested in spending them making this thing bullet proof rather than faster than a bullet what ive got: n42 block -> block needs to be bored because its tapered and a hone wont fix it n42 head random parts what im planning / need help (opinions on) .04 overbore flattop pistons a cam? really need help on this one too many options fuel delivery, i want something that will be reliable and simple to maintain and will work with the overbore flattop set up (i was hoping i could get away with rebuilt su's with some upgraded needles or something along those lines) is it worth it to get oversized valves or some head work? aka what would give me the most bang for my buck i know i need new gaskets, rings, and bearings, anything else essential to a rebuild to make reliable and worth the time? Quote Link to comment Share on other sites More sharing options...
Boog Posted February 4, 2015 Share Posted February 4, 2015 +1 on the flat tops, that with a mild cam should get you where you want to be. What L28 do you have? If its N42, just swapping flat tops in will get you to near 10:1 CR, of not over. There is a online calculator for L series compression ratio. Quote Link to comment Share on other sites More sharing options...
seattlejester Posted February 4, 2015 Share Posted February 4, 2015 Seems like you have some underlying problems if you blew up two motors. I would make sure to address the stuff remaining before slotting a new engine in. Make sure the coolant system is clean, have the radiator inspected/flushed new hoses, clamps, electric or new radiator fan. Have your electrical system updated a bit, relays, alternator, battery etc etc. Might help with the cold start problems and if you do end up running an electric fan it will help supply power to it. Making sure it gets good clean fuel at the correct pressure and volume. New lines, cleaned gas tank etc etc. For the engine rebuild... Throw in a new timing set, new spark plugs, new rotor, new cap, new coil, electronic ignition (not points, E12-80 module or what not), water pump, new studs (intake/exhaust), new hardware, new oil pump, and I can't imagine any problems. With the stock N42 cam and dished pistons and a fresh rebuild on my L28 with SU's, my friend driving my 240z pulled granny shifting at 5k pulled away from me driving his newer legacy. I had a 5 speed and a 4.11 gear ratio though. Quote Link to comment Share on other sites More sharing options...
nzarano Posted February 6, 2015 Author Share Posted February 6, 2015 i think my carbs / fuel system deff play a part in the issues I've had in the past with engines.... I plan on just putting the engine in the car, starting it up with the carbs to make sure there are no other issues then doing an sds refi install. Don't know if i just want to go refi or refi then turbo which is why im hesitant on the cam.... Electrical issues will hopefully be taken care of with the refi instal, but im debating a new body harness, don't want to deal with an ez wiring harness though so might just find somewhere to get a refurbished one so i can make it plug and play..... current debates are if i should do all the building after the machine shop takes care of all their work or if i should get them to build it to my specs ( leaning to that...) su's with some adjusted needles ( need ideas for this?) or efi? what to do with the body harness aka throw it away and get a new one or just roll with it i don't want this project to sit and get over my head thats my main concern keeping things within my realm and budget.... extra thoughts are what cam would be good for peppy street driving with this set up ( car will see high way time but nothing too crazy mostly around town and the longest highway journey it will take is 45-60mins) - to add to the pep should i look into a rear end? i have no clue what's on the car now... Brake lines and entire fuel system i feel need to be adjusted as well but i have no clue where to start with this... to start with the engine then do peripherals or do the opposite or try and just go very slow doing it all at the same time.... Quote Link to comment Share on other sites More sharing options...
seattlejester Posted February 7, 2015 Share Posted February 7, 2015 (edited) First off, I'm going to have to berate you a little bit, so put on your thick skin jacket. We have forum rules regarding proper capitalization, while it may seem tedious it is more professional and helps to read through posts. So please try your best to hit that shift key. I suggest against the use of so many ellipsis, it seems like you are trailing off a lot. I understand you want to accent that these are thoughts in progress, but if you don't put your thoughts in words it is hard to help out. If you don't put what you mean to say...yea...you know...stuff...right...difficult...yea... Onto your questions. i think my carbs / fuel system deff play a part in the issues I've had in the past with engines.... I plan on just putting the engine in the car, starting it up with the carbs to make sure there are no other issues then doing an sds refi install. Don't know if i just want to go refi or refi then turbo which is why im hesitant on the cam.... Electrical issues will hopefully be taken care of with the refi instal, but im debating a new body harness, don't want to deal with an ez wiring harness though so might just find somewhere to get a refurbished one so i can make it plug and play..... Why do you think the problem was with the carbs? Did you just throw on a set and go? Did you tune the carbs? Did you sync them? Did you check the mixture? Seems like you need to throw a wideband O2 sensor into the list of things you need. This will be good since you can use it if you go turbo later. You can ruin an engine pretty quickly if you are running real lean or real rich. So don't plan on just throwing on the carbs until you do EFI, make sure the carbs are functional first. Regarding electrics, don't throw the word hopefully around. That's a bad word. Fix the problem. Buy a multimeter and track down electrical issues. It takes less then 5 minutes to learn how to use one and what to look out for and if you have a coupon it's free sometimes at a harbor freight, or at most 8$. If you have some kind of short, putting in an expensive ECU is not going to fix the problem if anything you may burn out the ECU. Fix the harness now and make sure you wire it to accept future upgrades, a nice relay box, ignition powered relays etc will make your life easier. I don't know of any place that sells refurbished harnesses. Unless you can find someone who is going to run the exact same setup you will be running you will have to modify a harness. Starting from scratch with an EZ-harness is a good idea if you are good at mapping and keeping track or future proofing. If you are sure you don't want to do the work, find a good shop and let them know your build route, they can wire up a new harness with plugs to plug in new accessories down the line e.g. if you have a mechanical fuel pump now, they can wire up and run an ignition powered relay for the high pressure electric fuel pump you will need with a plug and a blank on the end. That way when you do upgrade they can just pull out the blank and plug in a fuel pump. Services of that nature can add up real quick though. Thinking starting at about 500 for bare bones and going up very quickly from there. current debates are if i should do all the building after the machine shop takes care of all their work or if i should get them to build it to my specs ( leaning to that...) Depends on how capable you are. If you are good at keeping track, can write down numbers, know how an engine works etc, the L-series is one of the easier engines to rebuild. You should leave the head to a shop, the bottom end is pretty easy to assemble and spec, although it can be daunting if it is your first time. The benefit if you do it yourself is you can write down every step and never doubt if a certain bolt was torqued or what the gap was etc etc. The downfall is if it breaks it is pretty much your own fault. su's with some adjusted needles ( need ideas for this?) or efi? The fuel curve from my experience with a L28 with a 4 bolt round top Su carbs is that it leans out as you go up in revs. Starts fairly rich around 10 or so at idle and leans out to 13 or 13.5 AFR as you reach the top end. That is with the stock needle and valve setup. You can buy SM needles which will kind of flatten the curve from the graphs I have seen to bring you to 11-12 idle and keep you around 12 or so all the way through the rev range. Once again just my experience and what I have seen. I thought the standard needles were fine. If you wanted a little bit better economy and safety at the top end, the SM might be the way to go. If you are going higher compression and you don't have access to decent gas, you may want to run the SM needles. what to do with the body harness aka throw it away and get a new one or just roll with it See above. i don't want this project to sit and get over my head thats my main concern keeping things within my realm and budget.... That is perfectly reasonable and quite intelligent to keep the project scope small. Big projects run away from you. With that said, either abandon the turbo plans or go straight towards it. Going from carbs to an EFI turbo will lead to very little overlap. Carb fuel line and fuel pumps are different from EFI stuff, and turbo stuff will need higher ratings then just run of the mill EFI stuff. First take stock of what you have. Will your chassis handle the power? Is it worth investing in this particular car? No point in having a rebuilt engine in a car if all your bushings are shot and your brake lines explode. Anecdotally, I had a friend that spent 4 grand on his engine rebuild. You could see through the floor in some spots, and large holes in the body. He ended up selling the car with having driven it very little as he couldn't afford the chassis work because of the engine. Plan out your projects to a "T" find out every nut, bolt, fitting, length of wiring, component, etc. Once you have an exact plan you can determine if it is achievable financially and time wise. If it isn't throw it on the back burner, but future proof your build so you can go for it one day. extra thoughts are what cam would be good for peppy street driving with this set up ( car will see high way time but nothing too crazy mostly around town and the longest highway journey it will take is 45-60mins) - to add to the pep should i look into a rear end? i have no clue what's on the car now... See above, take stock of what you have. If you don't know what you have how are you going to build on it? You are proposing on building a lego set without taking stock if you have hands or eyes. Take stock of what you have the knowledge will only help. Also see above, a turbo cam and an NA cam are quite different pick one and go for it. A rear end will make an NA car feel much faster as you take advantage of gearing over power, the down fall is that this will raise your highway cruising speed depending on what ratio you go with. Once again another item that will clash with future plans. If you get a high ratio your gears will be much shorter which will be useless for a turbo, in fact you would want the opposite on a turbo tall gears so you can take advantage of the turbo. Brake lines and entire fuel system i feel need to be adjusted as well but i have no clue where to start with this... to start with the engine then do peripherals or do the opposite or try and just go very slow doing it all at the same time.... While the engine is out, do the peripherals it is super easy to route fuel lines and brake lines when you don't have the drive line in the way. Unless your lines are in remarkably good shape I would say to order a replacement kit and a quality fuel/brake line bender and flaring tool. I think it takes less then weekend to replumb the car, brakes can really easily be done with CuNiFer lines, and you can run some 3/8 hard line which will supply plenty of fuel for really quite high power levels. In this regard I say to future proof it. I've redone my fuel system twice as I went from carb to EFI turbo. Even if you are staying carbs, building the system for EFI may be preferable just for better flow and hose/fitting options. Edited February 15, 2015 by seattlejester Quote Link to comment Share on other sites More sharing options...
malibud Posted February 12, 2015 Share Posted February 12, 2015 Nice right up Jester. Some good advice.... Quote Link to comment Share on other sites More sharing options...
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